1. Field of the Invention
The present invention relates to a cleaning apparatus, and more particularly to a cleaning apparatus for cleaning a mechanical part and the like (hereinafter, referred to as a work) with oil or the like adhering thereto by organic solvent vapor.
2. Description of the Prior Art
As this type of cleaning apparatus, there has conventionally been known a cleaning apparatus comprising a cleaning chamber of vacuum-tight structure, an organic solvent vapor generating tank (hereinafter, referred to as a vapor generating tank) communicated with the cleaning chamber via piping, and a vacuum pump for evacuating the cleaning chamber, such as shown in Japanese Patent Laid-Open Publication No. 54-113965 and Japanese Utility Model Laid-Open Publication No. 63-193588.
In this cleaning apparatus, organic solvent vapor (hereinafter, referred to as vapor) is supplied from the vapor generating tank into the cleaning chamber. The supplied vapor comes into contact with the surface of a work contained in the cleaning chamber, where it is condensed to make dew. Then the condensed organic solvent fluidly moves on the surface of the work to drop down, whereby the cleaning is executed.
However, the conventional cleaning apparatus as described above has the following problems.
That is, the temperature of the work surface increases gradually to become equal to that of the vapor, such that the vapor does not condense on the work. In this event vapor cleaning can no longer be executed, resulting in a shortage of cleaning time and therefore defective cleaning. As another problem, when the work is a hard-to-clean part such as parts having complex configurations, parts with high-viscosity oil adhering thereto, or parts with large amounts of oil adhering thereto, the cleaning cannot be resumed until the temperature of work surface decreases enough, by interrupting the vapor supply. As a result, longer processing time is involved.
As yet another problem, when the low-temperature used cleaning liquid accumulated in lower part of the cleaning chamber is returned to the vapor generating tank, the temperature of the organic solvent within the tank would become lower so that the amount of vapor generation decreases, so that the amount of vapor supply decreases. As a result, it would be impossible to achieve a sufficient cleaning, in particular, of the aforementioned hard-to-clean parts.